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SUMMARY:Stealth for Atoms:  Precision measurement in ultracold metastable helium atoms to test QED
DESCRIPTION:Helium is a favoured test bed for validating quantum electrodynamic theory through precision spectroscopic measurements.   We have previously measured transition rates in ultracold metastable helium atoms in order to test QED.  
 
More recently we have measured the first tune-out wavelength for metastable helium (PRL 115, 043004 (2015)).  This is the wavelength at which the atomic polarizability vanishes – effectively creating ‘stealth’ for atoms.  We utilise a novel, highly sensitive technique for precisely measuring the effect of perturbations in the trapping potential of magnetically confined atoms illuminated by an external laser light field.  At a wavelength of 413.0938(9stat.)(20syst.) nm we detect no effect on the trapping potential for atoms output-coupled from the trap, which compares well with the value predicted by theory 413.02(9) nm, but with two orders of magnitude greater precision.  This tune-out wavelength is very sensitive to non-relativistic QED effects, thereby providing motivation for more detailed theoretical investigations in order to test QED.

LOCATION:IQOQI lecture hall
DTSTART:20151030T141500
DTEND:20151030T151500
TZID: Europe/Vienna
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